Insect control apparatus



Nov. 18, 1958 M. c. KAHN ETAL 2,861,132

INSECT CONTROL APPARATUS Original Filed Feb. 21, 1950 3 Sheets-Sheet 1 I 2s 3O 32 VARIABLE I ATT. A A

PAD PAD l A I36 34 m FIG. 2

INVENTORS,

. Morton C. Kohn Williom H.O ffenhuuser,dr.

ATTORNEY Nov. 18, 1958 M. c. KAHN ETAL 2,861,132

INSECT CONTROL APPARATUS Original Filed Feb. 21, 1950 5 Sheets-Sheet 2 l8 l6 i i F|G.3 F|G.4 FIG.5

F|G.6 FIG.7

INVENTORS, Morton C. Kuhn William H.Offenhouserjr WWW ATTORNEY Nov. 18, 19 58 M. C. KAHN EI'AL INSECT CONTROL APPARATUS Original Filed Feb. 21, 1950 5 Sheets-Sheet 3 FIG.I2

INVENTORS, Morton C.Kohn William H.Offenhquser,jr.

ATTORNEY United StatesPatent O INSECT CONTROL APPARATUS Morton C..Kahn,.New York, N. Y., and William H. Otfenhauser, Jr., Fairfield County, Conn., assignors, by mesne. assignments, .to The Marcelle and Edwin M. Fleischmann Foundation, Inc Baltimore, Md, a corporation of Maryland Original application February 21, 1950, Serial No. 145,496. Divided andthis application July 25, 1952, Serial No. 300,845

1 Claim. (Cl. 179--100.1)

Thepresentrinventidn relates generally to insect control:and more especially'to apparatus and methods for interrupting the litecycle .of insects, such as mosquitoes, and. other arthropods'whichxare carriers of disease or involvedin the destruction or damagezof agricultural crops.

Means hitherto employed for destroying insect pests have been largelynon-selective with .the result that beneficialinsects such as hcney bees have been destroyed alongwith' harmful. insect .pests such as'mosquitoes, flies, gnats, locusts, etc. It-is contemplated by the present invention to provide a novel means for causing individuals of a-particular insectepest to alter their flight direction so that;they maybe destroyed;

Accordingly, one object :of the present invention isto provide novel andelfective means and methods for luring apreselected speciesof insects into a restricted area where they are destroyed'by lethal devices.

Still another. object of the invention is to provide novel,. sirnple and effective apparatus for attractingindividuals of ,a preselected species, genus or class of arthropods bymeans of sound waves attractive to the same, e. g., attracting members of one such species by means of sound waves characteristic of females of such species, and; destroying such individuals.

A still further and more specificobject of the invention is to provide a novel, simple and effective method for interrupting the life cycle of an undesirable species of insects byrproducinga-functional response upon an .external or internal organ of theindividuals of such species to direct such individuals into the sphere of influence of destructive means.

Still another object of the present-invention is to provide a novel, simple and; effective "means forinterrupting the life .cycleof insects 'of a-predetermined species comprisingmeans for producingsound wavepatterns characteristic of thefemale individuals ofdsuch species thereby. attracting individuals of such species toward the sound wave producingmeans and means for killing such attracted individuals at or adjacent such sound wave producing means.

A more particular object ofthe. present invention is to provide a novel, simple and effective method for interrup ting the life cycle of insects of a predetermined species which comprises .recording sounds characteristic: of the female individuals of such, species, reproducing such recorded. sound at a predetermined intensity for the purpose of*attracting the individuals of such, species toward thesource of the.reproduced sound and there destroying such attractedindividuals.

Astill further object of the present invention resides in means .for recording sounds characteristic of female arthropods, such as the female members of a preselected species of insect.

Astill further object of the invention comprises means for reproducingthe sound ,of arthropods such asfemale anopheles .or aedes mosquitoes and foremploying the same as. an insect-audible sound signal lure.

A still further object of the invention is to provide novel and effective methods and means for isolating sounds characteristic of individual insects of a preselected species and for recording predetermined portions thereof.

The foregoing and other objects and advantagesof'the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein preferred apparatus embodiments of the inventionare illustrated by way of example. It is to be expressly'understood, however, that the drawings are for purpose of i1- lustration and description only and are not to be construed as a limitation upon the invention.

The sounds produced by insects range in frequencies from the lower audio frequencies to supersonic frequencies, but, generally speaking, many insects emit sounds composed substantially of fundamental frequencies within the audio range.

lnthe following discussion particular reference will be made to mosquitoes as these insects are of special concern to us because of their ability to transmit many tropical diseases such as malaria, dengue fever, yellow fever, filariasis, and many others. However, the methods and apparatus described herein for destroying mosquitoes maybe correspondingly modified in order to destroy effectively such pests as flies, gnats, beetles, crickets, katydids, locusts, cicadas, tsetse flies and other anthropods of disease and agricultural importance.

It has been found that each species of arthropodof a particular genus emits a distinctive and identifiable sound, i. e., the different species within a particular arthropod genus, emit sounds which are peculiar to that particular species. This is not only believed to be true of many species of mosquitoes but also to be true of many other insect forms. Mosquitoes of different species may, for example, readily be identified by a trained car from the sound produced by them. The sound emitted by mosquitoes consists of a particular fundamental frequency rich'in harmonics and usually modulated at a very low frequency. The fundamental frequency of the sound o-fthe different'species of mosquitoes lies in the lower part of the audio range between approximately 250and 750 cycles per second. In some spectrograms taken of mosquito sounds as many as 15 distinctive frequency bands are recognizable, some much more pronounced than others. Thefundarnental frequency is often notthe dominant frequency. All mosquito sounds have vibrato effects. Some species emit tones with a single warble rate and other show a double warble modulation. The sound of the male individualsof a particular species of mosquitoes is distinct from the soundof femaleindividuals, the dominant frequency thereof being somewhat higher although with'very small difference in the fundamental frequency. Male sounds areusually more. bro-ken than the female sounds.

Because ofthe high harmonic content of mosquito sounds and the peculiar modulation thereof, it is difiicult to analyze the sound and duplicate it artifically. Experiments indicate, however, that the individuals of a particular species of mosquitoes are attracted by sounds containing only the dominant frequencies of the sound of the female of the same species.

For highly satisfactory and effective results in luring mosquitoes toward a mosquito trap the actual sound of a female mosquito is used. Due to the difficultyin using the amplified sound of a female mosquito as a lure ithas been found best permanently to record the sound of a female mosquito which recordings may then be duplicated and reproduced at will. A method. and apparatus for recording and reproducing insect sounds will be described hereinafter in order that the invention may be more fully understood.

optimum sound transfer efficiency.

In the accompanying drawings wherein like reference characters refer to like parts:

Fig. 1 is a view partly in section and partly in elevation of a microphone and sound chamber assembly;

I Fig. 1;

Fig. 4 is an elevational view of the sound chamber of Fig. 1;

Fig. 5 shows retaining clamp for the microphone of Fig. 3 and sound chamber of Fig. 4;

Fig. 6 shows an insect screen for closing the opening .of the sound chamber of Fig. 4;

Fig. 7- shows an extended plan view of the acoustical seal of Fig. 1;

; Figs. 8, 9 and 10 illustrate modified systems for re- .producing insect sounds;

Figs. ,11 and 12 illustrate two effective methods of .killing the attracted insects.

Referring now to Fig. l of the drawing there is shown a microphone and sound chamber assembly generally indicated at 10 mounted in a container 12 sealed by means of a cap 14 threaded thereon for acoustically shielding the assembly from the surrounding atmosphere.

The individual arthropod, such as an insect, whose .sound is to be recorded is placed in chamber 16 of assembly 10 and a microphone or transducer 18 is placed closely adjacent to the opening 17 of the chamber for In order to confine the arthropod in the recording chamber a fine mesh net 20 is placed over the opening thereof between the chamher and the microphone and secured to the chamber in some convenient manner such as by a rubber band, for example. The sound chamber 16 is shown in Fig. 4 as comprising a glass jar whose size will depend on the size of the arthropod to be confined therein and which should be made assmall as possible, due regard being taken, of

course, of the physical freedom required by the arthropod. The mesh of the net 20 shown in Fig. 6 for cover- .ing the chamber should be sufiiciently small to prevent the escape of the arthropod. The microphone 18 employed to pick up the sound from the arthropod emitted within the sound chamber and to produce an electrical signal amplitude modulated proportionally to the sensed sound. This microphone or transducer may be of any suitable type, for instance, it may be of the pressure type indicated in Fig. 3. The microphone is provided with a 1 shown at 10, in Fig. 1 and held in place by the cylindrical clamping device shown in Fig. 5 in order to prevent loss of sound energy from the chamber, and to shield the chamber and microphone from ambient noise.

Theoretically, the best geometrical form for a sound chamber is a sphere as this provides the smallest amount of external surface for the largest internal volume. The cylindrical chamber shown, however, has the most practical geometric form and was found to have satisfactory acoustical characteristics. The energy level of the sounds emitted by mosquitoes being very low, of the order of 10- watt in some species, it is necessary to provide the sound chamber with better than 60 decibels of insulation at 800 C. P. S. which, incidentally, was obtained with the sound chamber arrangement described herein. If additional acoustical insulation is found desirable, container 12 maybe nested within a further enclosure. In the'design of an enclosure the customary sequence of acoustical. elements should be adhered to for maximum acoustical effectiveness. Thus, the outside-of the endband having the best signal-to-noise ratio ob- .plified increases, because of the spectral energy distributraps with sound signals, the recording maybe broad-- closure should be highly sound reflecting, then a. ma terial which is highly sound absorbing, and so on until i the desired acoustical insulation for the sound chamber" is achieved. If high efiiciency, of sound signal conver' Q sion is obtained, it is apparent that the signal-to-noise ratio of the electrical signal supplied by the microphone can be improved effectively by further reduction of the ambient'noise by improving the acoustical filter. a

In selecting a microphone it is important that it has a I good high frequency response and rather poor low frequency response, i. e., is more sensitive to high frequency than to low frequency audible sound signals, and that; it has a geometrical shape making it suitable for close coupling with the sound chamber.

The amplifiers used for amplifying the signal picked; up by the microphone may be any modified high fidelity, commercial type having a suitable amplification-in the. V case of mosquitoes a total amplification of morethan tainable. The final signal should have a signal-to-noise ratio of at least 40 db to assure suitable performance.

The amplifier and recorder system illustrated in Fig. '2 comprises generally the microphone pickup 18, a high, amplification amplifier stage 26, a variable highattenuation pad 28, a second amplification stage 30, a fixed low attenuation 32, a third amplification stage 34 and a re corder 36. The variable attenuation pad 28 is used as: gain control for the system. The low attenuation pad 32 was inserted to improve the frequency characteristics of the amplifier system. The frequency response curve of the amplifier should be characterized by rising slope with" increasing frequency, i. e., the amplificationfactor in-'= creases as the frequency of the audible signal being amtion of mosquito sounds. The high energy compof nents are located higher in the audio frequency spectrum 7 and there are more transients than in the human voice, for example. A 6 db per octave rise in the amplifier response curve has been found to be satisfactory.

It has been found that effective recording results wet obtained by using a high quality recording equipment inscribing on standard acetate discs but other satisfactory. recording media may also be utilized such as magnetic.

tapes.

The recording of the sound of the mosquito or other arthropod should be begun after the insect or arthropod confined in the sound chamber has chirped or emitted; its characteristic sounds several times within a few min A utes which. in the case of Anopheles albimanus, usually. occurs near sunrise and sunset. The recorded discs should be edited to eliminate duplication. Selected portions should then be re-recorded, repeating a selected-sequence until the disc is filled. Thus, by using a standard record changer, for example, the recording may be repeated as long as it is desired. A substantial number of such recordings has been produced by applicants and is now available.

In order to lure male (or female) individuals offa preselected insect species into an insect trap such a re cording is played continuously during the normal activity period of the particular insect species, and the tran scribed sound is amplified and broadcast through a high; quality audio speaker located behind the trap. f

In Fig. 8 such a reproducing system is shown as comprising a pickup 36, an audio amplifier 38 and a loud-. speaker 40. If it is desired to. bait a plurality of insect cast over a radio transmitting station and. reproduced by a commercial-receiver 42 having a speaker 44 as. shown in Fig. 9. Fig. 10 indicates a system .for transmitting an artificial insect or other arthropod signal de veloped in a signal generator 46, amplified by an amph fier 48 and transmitted by an audio speaker 50.

Various means. and methods may be employedfor trapping and for killing the insects attracted by the broad wast-sound. -iIt=isideemedipreferable totkillithe insects by e an electric screen; although i other tmethods a of killing rthm such as-by radiation, by-chemicafmeansisuch as' an insect killing.sprayolfimistpfor example, by! mechanical nions-such: as. by crushing: adhesion. or:-entrapment, or

by firetraps may be foufid moreocorivenientl depending upon location. When it is desired to examine the attracted insects, they should be killed by a method which will not mutilate them.

An insect trap of the supersonic radiation type is illustrated in Fig. 11. A supersonic generator such as an air-actuated Hartman whistle is indicated at 52 located at the focal point of a collective reflector 54 mounted adjacent to a loudspeaker 56 on a support 57 and aimed so as to intercept the path of the insects migrating toward the loudspeaker. Supersonic radiation of the correct waveform, pitch and intensity is fatal to insects while being quite harmless to human beings and large animals. Other types of supersonic generators may, of course, be employed in the place of the Hartman whistle. Several sets of supersonic generator and reflector combinations may be employed to produce a field pattern completely encompassing the loudspeaker.

Another convenient insect trap is illustrated in Fig. 12 as comprising a loudspeaker 58 mounted within a wire screen having spaced wires 60 alternately maintained at a high potential with respect to each other. The mosquito or other insect or arthropod does not have to touch the wires to be killed. Passing between the wires without touching them is lethal and hence it is immaterial if the arthropod passes between the wires without touching any of them as is common when the wire spacing is of the order indicated. When an arthropod passes between two spaced wires, the voltage is first increased to the point where arc-over occurs due to the high voltage, following which the voltage then becomes somewhat decreased, say by about and thus the presence of the insect or other arthropod in the electric field between adjacent wires causes breakdown without any touching of the wires whatever. The spacing between adjacent oppositely charged wires should be of the order of A1 of an inch in order to kill mosquitoes, and a voltage between adjacent wires of about 5,000 to 10,000 volts has been found satisfactory and may be supplied by a step-up transformer such as indicated at 62. The loudspeaker alone may be mounted within the charged wire cage and actuated from a remote point, or a complete reproducing system such as shown in Figs. 8, 9 and 10 may be enclosed therein.

Thus, in order to destroy arthropods of a particular species, for example, a particular species of mosquitoes such as the malaria-carrying Anopheles albimanus, a female individual of that particular species is selected and the sound thereof is recorded as set forth above and, for example, as illustrated in Figs. 1 and 2. The recorded sound is reproduced in a convenient manner such as by one of the apparatuses illustrated in Figs. 8, 9 or 10 and used in conjunction with a mosquito trap, such as illustrated in Figs. 11 or 12 and located in an infested area, at sunset and sunrise when this particular species of mosquito has been found to be especially active, and correspondingly for other arthropods. The invention may in general be employed and practiced at any time even though peak activity is absent since in this way the insect or arthropod population may be reducted to the infection threshold or below.

The catch of individuals of the species will vary for different species. Insects of either sex may be attracted by sound but for bioligical reasons the attraction of male individuals by female sounds has been found to be much more efiective but calls other than sex calls, e. g., food calls, may be employed. The number of females caught in the trap will be far larger than the number which would have been destroyed in the absence 6 of a soundlure; by. random.-.fiight"alone,.zthusiiindicating that to some extent femalesas wellasmales of the species are attracted by the sound. '-It has" beendetermined by actualteststhat by usingthemethdda-nd apparatus as deit may also be employed for private use indestroying insect pests within a limited area in homes and gardens. For example, if a standard radio broadcast station were to transmit continuously mosquito inscriptions, ordinary home receivers turned down sufficiently so as not to disturb the sleep' of human beings may be used to lure insects into conveniently located mosquito traps or areas or fields rendered lethal by chemical, mechanical or radiation means.

In this connection it should be added that there is a critical intensity of sound beyond which the insects or other arthropods may be repelled rather than attracted. For optimum effectiveness the maximum intensity of the sound lure should be somewhat below this critical intensity at the location of the insect trap. Optimum performance is indicated at a volume intensity of approximately 10 V. U. (volume units) as measured on an American Standard Electrical Volume Indicating Meter at the location of the trap, when fed into a Western Electric D-l7349l loudspeaker or the equivalent.

Sound may also be used to repel insects or other arthropods. As above pointed out, when a certain intensity of the insect sound is exceeded, the insects will be repelled. Moreover, when a signal having a certain frequency is used, insects of some species will be repelled. Such frequency may be experimentally determined for the particular species or genus in question, and can be expected to be found to be higher than the tenth harmonic of the fundamental frequency of the sound of such insects as was determined to be the case for Coleoptera (Japanese beetles).

Although only one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention which is defined by the appended claim.

This is a division of application S. N. 145,496, filed February 21, 1950, for Improvement in Insect Control Apparatus and Methods.

We claim:

In a system for arthropod insect control utilizing a recorded insect-audible sound signal as the sole insect lure, the improved means for producing said recorded sound signal which comprises a small-volume sound chamber, acoustic insulation substantially surrounding said chamber for minimizing entry thereinto of external ambient sounds, a sound transducer in said chamber for producing an electrical signal, amplitude-modulated proportionally to sound signals originating in said chamber and sensed by the transducer, said transducer being characterized by a higher sensitivity to high frequency than to low frequency audible sound signals, electrical signal amplifying and modifying means electrically connected to said sound transducer having an audio amplifier with an overall response characteristic which rises with increasing audible signal frequency, and recording means electrically connected to said signal amplifying and modifying means for producing a substantially undistorted reproducible record of the output signal of said signal amplifying means.

(References on following page) LITIUNITED STATESLPATENTS f :1"96b,0s4 Folnier eta1. May 22, 1904 Tm plcal Medlcme, vol. 29, 1949, p.. 811. v 1,6453% Roger's 1927 5 Elements of Sound Recording, by Frayne and Wolfe, Q FOREIGN PATENTS pp. 255-257, 395 and 396 (1949). V

3,018 Great Britain June '24, 1945 1 The Songs of Insects, G. W. Pierce, chapter IV 10 (1948).

References Cited in the file of this patent The First Field Tests of Recorded Mosquito Sounds 1 Used for Mosquito Destruction, by MortonC. and William Offenhauser, In, American Journal: of

OTHER REFERENCES 

